Most of us will try a diet some time during our lives. Often when I talk about steps needed to treat a heart disease, patients will say they know they need to lose weight and plan to start a diet. In my clinic patients bring in all sorts of diets to discuss with me. Most diets that I review involve limiting choices. For example, let’s propose a cupcake diet. You eat cupcakes alone for breakfast, lunch, dinner, and snacks, and have as many as you want. However, eating cupcakes day after day is not easy and what was once enjoyable becomes less so. The consequence is that you eat less and less each day. By doing so, your calories are reduced and you lose weight. Some of these diets promote eating meat frequently, others remove all grains and breads, and some involve a certain vegetable. Long-term compliance can be challenging and maintaining the weight loss can be difficult.
Physicians have used diets to prevent or treat heart disease for over 50 years. A recent paper discussed 65 years of diet knowledge, an excellent paper and a fantastic resource, summarized here.
Diets to Prevent Coronary Heart Disease 1957-2013
In 1957, Ancil Keys reported in JAMA evidence that diet accounted for variability of coronary artery disease. In addition, poor choices in sicker patients came with elevated cholesterol levels. The American Heart Association nutrition committee stated that diet contributes to coronary artery disease and diets high in fat may be associated with disease progression. They recommended:
- Daily fat intake of less than 30 percent of the daily calories
- Saturated fat less than 10 percent of daily calories
- Cholesterol to less than 300 mg a day
But Americans continued to consume 38-40 percent of their daily calories from fat and 450-533 grams of cholesterol.
Lessons learned: Recommendations made to physicians and the public were not followed.
Multiple Risk Factor Interventions
The Multiple Risk Factor Intervention Trial (Low Fat Diet to Reduce Heart Disease in High Risk Men) included 12,886 high-risk men for (high blood pressure, high cholesterol, and smoking), randomized either to:
- Saturated fat of less than 10 percent of daily calories, cholesterol less than 300 mg/d, and an increase of polyunsaturated fat to greater than 10 percent, or
- Their prior diet
While daily consumption of fat and cholesterol were reduced to the study goals, unfortunately the authors failed to find lower stroke or heart disease related death with the aggressive diet.
Lessons learned: Perhaps the optimal diet is not about the amount of fat consumed, but the type of fat.
Experiment of Heart Attack Survival
This study was of 406 patients who had heart attack or acute myocardial infarction randomized to 1 of 2 diets, in the hospital for up to 30 days after their heart attack:
- Increased fruits, vegetables, nuts, and fish or
- Reduced meat, eggs, hydrogenated oils, and fat and replacing these with meat substitutes, soybeans, and nut oils
After 1 year the group randomized to fruits, vegetables, nuts and fish had lost more weight, had a greater reduction in cholesterol levels, and had few heart attacks and higher survival rates.
Lessons learned: A balanced, low fat diet was better than just trying to lower fat. Diet can quickly impact heart-related disease progression.
Lyon Diet Heart Study
In this study on impact of diet on heart disease progression, 605 heart attack survivors were randomized to:
- Mediterranean diet (low in most meats, but high in olive oil, legumes, vegetables, fish, and fruits), or
- Low fat diet.
Those consuming a Mediterranean diet had a 72 percent reduction in heart attacks and death.
Lesson learned: In people that have heart disease, diet is no longer something to study, but an essential part of the treatment with an impact as great or greater than most medications.
PREvención con DIeta MEDiterránean Study (PREDIMED study)
In a study of 7,447 men and women who had cardiovascular risk factors, the Mediterranean diet was studied to see if it could prevent the disease. The study participants were randomized to 1 of 3 diets:
- Mediterranean diet with additional extra virgin olive oil
- Mediterranean diet supplemented with mixed nuts, or
- Low-fat diet
Those on a Mediterranean diet, regardless of if it was supplemented with nuts or more olive oil, had significantly lower rates of stroke. They also had lower rates of heart attacks and death.
Lessons learned: Dietary choices in people who are at risk of heart disease could prevent it. As I mentioned in my prior column, the best treatment for heart disease is prevention.
The Ornish Diet
The Ornish diet is a very low-fat vegetarian diet; only 10 percent of the diet is from fat, and the total cholesterol is <5 mg per day. In a study of patients with known coronary artery disease, this diet actually result in a disease regression in 82 percent at 1 year and in those that remained compliant further decreased at 5 years.
Lessons learned: First, perhaps most heart disease does not have to occur at all and can be prevented with daily choices. Next, even if disease has developed it is never too late to change and aggressive changes may have profound benefits.
What Have We Learned in Over 50 Years of Diets?
An abundance of evidence shows that Mediterranean diets are cardioprotective, and diet is much more than fat. If you are considering a diet, choose one that you can maintain over a lifetime and that involves a variety of healthy food sources. As you take on a diet add lifestyle changes that include exercise, improving sleep habits, and reducing stress.
One of the strengths of a whole diet, such as the Mediterranean diet, is that it contains many food choices that have unique beneficial properties and so meals and snacks can be varied and long-term compliance becomes easier. This is best shown in the multiple studies present herein that show high rates of long-term compliance to the diet and sustained benefits for your heart.